Alpha

Can I buy just the lower unit for my Alpha Gen II?

Yes, the Gen II lower unit is available on its own if your upper is sound. That's a common choice after skeg or case damage, since metal from a damaged lower normally isn't pushed up into the upper. Pull the top cap off your upper - there's just an O-ring sealing it - and inspect before deciding. Confirm your ratio with the drive serial number first.

Can I buy just the upper unit for an Alpha Gen I?

Yes, the Gen I upper is available separately, as is the lower - plenty of customers replace only the half that's failed. Confirm your ratio first from the drive serial number or a gear tooth count, because the upper and lower have to match. Note that if your old ratio is listed as 1.84, that was replaced by our 1.81, and 1.50 by our 1.47.

Can I fit a Gen II drive onto my Gen I transom assembly?

No. To convert to Gen II you have to change the transom assembly as well - a Gen II drive will not go onto a Gen I transom. The flywheel and bellhousing don't change, but if the engine is already out and the coupler is original, we'd recommend replacing the drive coupler while you're in there.

Can I mix an SEI upper with a MerCruiser lower, or the other way round?

Yes - our uppers and lowers interchange with the OE uppers and lowers without an issue, so you can replace just the half you need. A lot of customers buy only the lower and keep their existing MerCruiser upper. The ratio still has to match across both halves, so confirm it before ordering.

Do you make a drive for a 1970s MerCruiser inline 6?

Yes - the mid-1970s inline 6 applications around 165 HP typically take our Gen I complete drive in the 1.62 old-style ratio. Send us the outdrive serial number and we'll confirm. We'd recommend the Gen I installation kit alongside it.

Do you make a replacement drive for a MerCruiser 3.7L or 470?

Yes - the 3.7L and the 470 are typically the 1.81 ratio in our Gen I range, and the inline 4-cylinder 170 HP applications land there too. We'd still want the drive serial number or a gear tooth count to confirm before shipping, since the ratio is what determines whether the boat props correctly.

Do you make a replacement drive for a MerCruiser Alpha One (Gen I)?

Yes. We make complete Alpha One Gen I drives and lower units that fit 1972-1990 applications, in the correct ratio for your engine (for example 1.47 for a 5.7L V8, 1.94 for a 3.0L). Give us your drive serial number or engine details and we'll match the exact ratio and get you the right part.

Do you make a replacement drive for a MerCruiser Alpha One Gen I with a 3.0L?

Yes - the 3.0L applications from the mid-1980s typically take our Gen I complete drive in the 1.94 ratio. Send us the drive serial number and we'll confirm; if the number has worn off, drain the upper, pull the top cap and count the teeth on the two gears and we'll match it from that.

Do you make a replacement drive for a MerCruiser Alpha One Gen I with a 5.7L V8?

Yes - a V8 application like a 5.7 or a 302 is normally the 1.47 ratio in our Gen I complete drive. It's worth double-checking by counting the teeth in the upper if you can't read the drive serial. Your original shift cables will work with it as long as they're still in good condition. We'd recommend adding the Gen I installation kit rather than reusing old hardware.

Do you make a replacement drive for a MerCruiser Alpha One Gen II with a 4.3L or 5.0L?

Yes. The Gen II complete drives cover the 1991-and-newer Alpha applications. As a rule of thumb a 4.3L is usually the 1.81 ratio and a 5.0L usually the 1.62 - but treat that as a starting point, not a guarantee, because the ratio is the one thing we won't guess at. Send us the drive serial number (port side of the upper, on or under the MerCruiser sticker) and we'll look it up exactly. Price is the same across the ratios.

Do you make a replacement drive for a MerCruiser Alpha One Gen II?

Yes. We make Gen II (1991-and-newer) complete drives and lower units, matched to your gear ratio. Confirm the ratio from your drive serial number (or count the gear teeth) and we'll point you to the correct SE116-series unit.

Do you sell a transom assembly for an Alpha One Gen I?

Our new transom assemblies are the Alpha Gen II and the Bravo. Going from a Gen I to one of the newer transom assemblies is generally not too difficult, but it starts with a solid platform - the transom and stringers have to be sound. Beyond that there are two additional holes to drill in the transom mounting, and we'd recommend using a template. The steering ram is reused or bought new, as is the trim pump. Call us at 813-925-7127 and we'll walk through what your boat needs.

Do you sell the inner transom plate on its own?

No - the inner plate is only supplied as part of the complete transom assembly. Our Bravo transom replacement bolts up exactly the same as the original and comes with all new hardware, so if the plate is corroded the complete assembly is the route.

Does a MerCruiser V8 use the same lower unit as a 4-cylinder?

Yes - from 1968 to 1997 the V8 and the 4-cylinder use the same lower unit, as long as both are standard rotation. So a lower advertised for a V8 application will serve a 4-cylinder of that era. What does differ is the upper, where the gear ratio lives, so confirm your ratio from the drive serial number before ordering.

I have a pre-Alpha drive with a pin on top of the driveshaft - can I use your lower unit?

Yes, and you can change just the lower without replacing the whole drive. The pin on your old shaft was needed for the gears in the original lower; our lower is designed differently and doesn't need it. Send us a photo of the driveshaft splines if you want us to confirm which style you have before ordering.

My 454 is rated at 330 HP - will an Alpha drive handle it?

That combination existed only briefly. MerCruiser paired the 330 HP 454 with the Alpha for a few short years and then stopped, rating the Alpha to 300 HP thereafter - and neither the OEM nor we warranty an Alpha above 300 HP. On that specific pairing we'd expect a 1.32 gear ratio. If you're running that much power we'd point you to a Bravo instead. Send us photos of the drive and we'll confirm what you have.

My twin engines are different sizes - will your lowers work on both?

The lowers can be the same and both can be swapped for ours, but be aware of a knock-on issue: if one boat has a 5.0L upper and the other a 5.7L upper, the gear tooth counts differ between them. That means the two engines will need different throttle positions to run in sync. It's not a fault, it's a consequence of the mismatched uppers - worth knowing before you chase a synchronisation problem.

Which MerCruiser sterndrives does the SE106 replace?

The SE106 replaces most MerCruiser sterndrives from 120 to 260 HP built 1967 to 1990 - the Alpha One Gen I era. Two conditions: your drive must have trim and tilt to use our replacement, and if it's a 1967 to 1969 you need to verify you have 13 splines on the upper driveshaft. We publish an SE106 application guide that lists the coverage in full. Send us your drive serial number and we'll confirm the exact ratio.

Will an Alpha drive handle a 383 stroker?

A 383 stroker isn't so powerful that the Alpha wouldn't hold up, and there are a lot of people running exactly that combination. We wouldn't attach our warranty to it, so that's your call to make. Bear in mind a Bravo is physically bigger and absorbs more power to turn, so you may not gain as much performance from switching as you'd expect.

Will your upper unit work with my original MerCruiser lower?

Yes - our uppers match up fine with an OE lower, and equally our lowers work with an OE upper. That makes it practical to replace just the half that's failed after a rebuild or an impact. The ratio has to match across the two halves, so send us the drive serial number and we'll verify before you order.